Using the same tool, we may create the indicator of play back:

Create Hi-Tech mp3 player interface in Photoshop CS

Create Hi-Tech mp3 player interface in Photoshop CS

Fill 0% on the layers
Blending Options-Drop Shadow

Create Hi-Tech mp3 player interface in Photoshop CS

Blending
Options-Inner Shadow

Create Hi-Tech mp3 player interface in Photoshop CS

Blending Options-Gradient Overlay

Create Hi-Tech mp3 player interface in Photoshop CS